Process of vulcanization.



W. G. HILL.

PROCESS OF VULGANIZATION.

APPLICATION FILED FEB.12, 1913.

I 1,090,535, Patented Mar.17,1914.

2 SHEETSBHEET l.

wiinea'ses W. G. HILL.

PROCESS OF VULGANIZATION. APPLICATION nun 212.12, 191s 1,()9(),535 Patented Mar. 17, 1914:.

2 SHEETS-SHEET Z afriv 'r enrich.

WILLIAM G. HILL, or HUDSON, MASSACHUSETTS,ASSIGNOR T0 APSLEY nU BER COIVILANY, or HUDSON, MASSACHUSETTS, A CORPORATION or MASSACHUSETTS.

raocnss or vULoAnIza'rIoN.

Specification of Letters'Patent. Patented B131 1*? 1914 Application fired February 12, 1913.; Serial m. 747,898.

To all whom it may concern lie it known that I, lVILLIAM G. HILL, a citizen of the United States, residing at. l'l'udson, county of llliddlesex, State of Massachnsetts, haveinvented a certain new and useful ln'iproveinent in Processes of Vulcanization, of u hich the following is a specification, reference being bad therein to the accompanying drawings.

.My invention has for its object an improved process for the vulcanization of rubber compounds or articles made therefrom. The method will be clearly understood from the following description taken in connection with the accompanying drawings, of

the way in which it is employed in practice,-

and the novel features thereof are pointed out and clearly defined in the claims at the, close of this specification.

In the drawings, Figure 1 is a vertical lengthwise section of a vulcanizer adapted for steam vulcanization. Fig. 2 is a transiersc section thereof on line 2-2. Fig. 1. Fig. 3 is a side elevation showing arubber shoe assembled on a last ready for vulcaniznticn. Fig. l is a side elevation showing a shoe on a last within a. flexible envelop from which the air has been partially exhausted, and the connection through which the air may be exhausted. Fig. 5 is a front or end view of the envelop containing the shoe and last shown in Fig. 4. Fig. 6 is a plan and Fig. *1 side elevation of a closure device for closing the flexible envelop to preventi the ingress of air. In the vulcanization of articles, such for example as boots and shoes which are made from rubber compounds, the article is first formed from the unvulcanized material, the parts being completely assembled with the fabric lining, etc., in place on aproperlast, as is well known to those skilled in the art.

able support on a car which is run intola vulcanizer or chamber which is then closed and the temperature within the chamber is .then gradually raised, usually by means of heat from steam coils, until it reaches about 270 Fahrenheit. This dry heat process is the one in common use, and the time consumed in vulcanizing an article such as a. shoe by this process is from six to eight hours.

Another process in common. use is the steam process, which is used chiefly in. connection with the vulcanizatiar of mechanical rubber goods. In this process the articles are surrounded by steaniand the process is not therefore adaptablefor the vulcaniza tion ofsuclrarticles as rubber shoes for the reason that the moisture and Water of condensation has Ya bad effect upon the fabrics which are used. a's'linings and also injures the surface of the shoes by causing it to be pitted and in general ofpoor finish;

Other processes contemplate the vulcanization of the goods while surrounded ,by air or other'gases under pressure andstill others combine the use of gases under-pressure followed by the use of steam. .The use of gases under pressure tends to compact and ,densify the material being vulcanized which is desirable. When airor gas has been used under. pressure for a sufiicient time to partiallycure the material being vulcanized or until thecharacter of the material being treated'has-to a degree become fixed,the danger .of pitting from a subsequent applithen be completed by the employmentof steam, propcrprecautions being taken to prevent the steam from access-to the'fabric linings which are used. Some of these methodsare expensive in operation and a unifornrvulcanizing temperature, which isdesirable, is obtained with difl'iculty. They are further open to other objections of a more or less serious character.

By still another vulcanizing proccsswhich I have employed (as described in Letters 'latent of'the United States granted to me No. (561,178) "I surround the article to be vulcanized by an inert gas under pressure that is .a gas inwvhich'thereiis no free oxygen. This process is difficult of application and expensive although the results obtained are desirable, namely the compacting and deusifyingmf the article due to the pressure of the'inel't gas and the prevention of all access of free oxygen to the article being vulcanized. in all the processes of vulcanizationnmv used or contemplated so far as'known to me, with the exception of my process referred to, in which I employinert gas, the article being vulcanized is'ergposed, to the deleterious effect otthisfree o 'tygen. For example in the process now conn'noniy employed to which have referred, and which is known as the dry heat process, the air surrounding the article being vulcanized cationof steamis avoided, and the cure may contains approxin1ately2O% of free :oxygen. This exerts a very harmful action upon the rubber compounds, especially when they are jployed during vulcanization.

subjected to the high temperatures em- VVhile the necessary heat is being applied to cause the reaction between the sulfur and rubber to proceed, simultaneouslythe heat in connect1on with the oxygen contained 1n the anus oxidizing and in uring the rubber; If this oxidizing can be eliminated the beneficial results are most marked, andthe strength and wearing qualities and general durability- .of the product are much increased. This is true when high grade rubber is employed in the compound, and more markedly sowhen the low; grades are employed, since the cheaper rubbers are apparently less able to withstand oxidation.

By the employment of my improved process hereinafter described I exclude free oxygen wholly or in very .large part from the article while it is being vulcanized; 1 subject the article to pressure thereby-'densify' ing'audcompacting it and by protecting the 'article I am enabledto use any heating agent as ,for example, steam, so that the necessary .hcat may be applied more quickly and the' consequent time of vulcanization very ma terially reduced.

.Referring to the drawings A.- designates avulcanizing -chamber which may be of any wellknown shape or construction. It is preferably however a chamber into which .livc steam may be introduced and therefore should be constructe; to contain live steam to producea temperature of 280 to 300 dc grees with the accompanying pressures of from 30 't0'40 lbs. or thcrca-hout to the'square inch. Such aehamh'er is shown Figs. 1 and 2.'-An airy/escape valve 2 is provided-so thatthe air within the vulcanizcr may he allowed tocsczipe-as the stcameuters. Means not shown, are also provided totake care of any water of cmidensation, and heating coils f (also not shown) are preferably placed within the vulcanizer so-that the interior may be heated prior to the introduction of steam, and thus condcnsationdiminished. A

thermometer and gage i and G respectively are provided as is common in vulcgmizers- All of these deviccsare ofgcommoli' and well (3. ()themwelhknown means of supporting" the antirles to'he vulcanized within the vulcanizlng clnnnheuumy-he employed.

The article to be vulcanized, for example which may be re a shoe, is prepared on a last L in the usual way, and when thus prepared-will be of the. appearance shown Fig. 3 ifthe shoe isof'the shape there indicated. The shoe and last are then placed in 9. ba g or envelop D of flexible material which is impervious to air or steam and'which can be sealed against the ingress of air. -As a material for the manufacture of this envelop I have employed a th in strong rubber fabric, the fabric face of the materialforming the exterior of the en while the interior is formed'by the.

velop,

smooth rubber surface This envelop; may

be simply of rectan' ular shape, but must be j -of. ample size sotiat its interior-may be' brought into contact with the irregular sides v of the shoe when the shoe is placed therein.

The envelop may beprovided with a simple exhaust connection by meansof which when l the envelop is sealed the air eontainedihere- 111 may be withdrawnor pumped out. A

preferable formof air exhaust connection is shown Fi 4. This eomprisesascrewstud '20 which as screwed into the top of the last and which'is provided with ab'oss QLwhich lies on the top ofthe last when thescrew,

stud 20 is'in position; The top of thefscrew stud 20 ishol o'w and an opening connectin with the hollow interior top of the sai screw stud 20 is shown at 22. This opening 22 is through the boss 21 above referred to. I

The pur ose of the boss 21 is'tohold .the envelopoi the top of the last connection 6 provided with. a couplin union 23 is provided for connection with to} stud v and permit a'1 space for the exhaust opening .22, F A hooked,

20 and underneath, the union 23 is placed a i washer 24 which when the union is screwed down will he forced against the cnvelo around th opening therein through which the stud 20 projects, and will serve to close and seal the opening. The connection 6 is providcd with a shut-ofi valvcoli') and the 'upper free end of the *onne ction (iis'of' the hookedsliape as showi Fig-t so that the .connection may also. be utilizpd to hang. the shoe and envelop on the rack 111511115 vulcanizcr. I H

By the means above described a convenlenj; exhaust connection is providedas also a-convenient means for suspending the shoe.z'.

iuthe vulcanizer, the weight of the suspenslon coming upon the wooden last and notupon the flexible surroundingenvelop vhere ina'fterdescribcd. I

. The shoe.assembled-oathslast asabove.

dcscribed'is placed within thewenvelop, the.

open end of-the latter-through which the shoe and last have beeninserted is then sealed 1n any well; known manner .as by means of rubber cement, or the-like. To

provide a means of quickly closing and sealing the open end of the envelop and one 'eatedly used (the envelop being designed or repeated use with suc- 1 i will collapse,

cessive shoes.) I provide a device shown -7.- This consists of a frame comprising a'bottomstrip of metal 26 and a top strip 27 connected at one end by means of a screw bolt 28 and at the other end by means of two screw bolts 29 and 30. An-

other intermediate clamping strip 31 is. provided with a hole at one end through which the bolt 28 passes aid with two holes at the other end through Which-bolts :29 and 30 pass. The clamping strip 31is free to move on the said bolts toward or from the bottom strip 26. The top-lstrip 2'? has a wedge shape face and alter the ends of the e11- velop indicated at 33 Fig. 10 are inserted between the bottom strip 26 and the clamping strip 31, a wedgeiid is inserted from the end of the frame between the studs 29 and 30 and pushed home to. the position shown in said Figs. 6 and 7. This wedge forces the clamping strip 31 firmly and uniformly against the two sides of the end 33 of the envelop which are clamped between the said clamping strip 31 and the bottom strip 26 and closes and seals the said end against the ingress of air. After the envelop has been thus closed and sealed an air suction device is coupled to the connection '6, if the air exhaust connection be: of the form' shown F ig. 4, and the air is exhausted from the envelop to a substantial extent.

It will'be understood that in placing the shoe and last Within the envelop when the last is provided witha fixed screw stud connection 20, asshqwn' Fig. 4:, there is an opening in one side of the envelop properly located which can he slipped over the projecting end of the stud 20 after which the washer 24 and the connection 6 With its union 23 are secured to the upper end of the stud 20 and the opening in the side the envelop through which the stud projects} is thus closed and sealed.

In practice I have found that I can readily obtain within the envelop from 20 to 21 inches of vacuum which corresponds with a pressure of about 10 lbs. to the square inch. As-the air is exhausted the envelop and the walls thereof are forced into intimate contact with the irregular exterior of the 'shoe, as shown Fig.

5. The operator manipulates the envelop so that it will he as smoothly as=plossilole over all parts of the exterior of the shoe and'thesides or walls of the envelop will meet along a central line extending from the toe up the front of the shoe to the top and from the heel up the back of the shoe to the top. This is of importance, because Where the two sides of the envelop unite there will be a sli"l1t space in which less pressure will be app-Ltd to the shoe surface and there will consequently be a slight projection or fin formed on the shoe. For thisreason it is desirable that this meeting point of. the sides sho'e.

of the envelop and the consequent projection or fin should be central of the Shoe from the toe to the top and from the heel to the top. Such a projection, which is relatively slight, when thus located does not interfere substantially with the appearance of the shoe. By practice the skill of the operator in manipulating the envelop isincreased and this together with the employment of certain aids in locating the shoe within the envelop which are hereinafter described, will tend to produce a more accurate and per-feet union of the sides of the envelop .over the shoe, and thus to diminish the consequent fin or projection which is formed. If considered desirable to wholly eliminate this tin or projection this may be accomstrip of vulcanized rubber or similar smooth material not affected by the heat -canization which is laid on the shoe themeeting point of the sides of the en velop. The shoe thus incased in its onvelop is by the partial exhaustion of the air subjected to a pressure of about 10 lbs. to the square inch, which tends to density and compact the rubber compound of which it is formed. Thus prepared the envelop containing the shoe is laced within the vulcanizing chamber A, see Figs. 1 and 2, and live steam allowed to enter until the temperature has risen to about 280 degrees with a consequent pressure of about 30 lbs. to the square inch. Under thistemperature and pressure the curing or vulcanizingol the shoe will be effected in about two hours. Free oxygen is substantially excluded from the rubber compound being vulcanized, moisture is excluded, and no injury results .therefore' to fabrics employed, such as the linings of the shoe, or to the surface of the The compound is densified and firmly compacted by the molding pressure, and the application of the pressure through the en velop. no matter how flexible the envelop may be, causes a very perfect union of the parts of the shoe, forexample the sole and upper, so that the parts are all blended into one homogeneous whole. Exhausting the air from the envelop removes the air from between the liniugaud the adjacent surfaces of the compound of-t-he shoe. With "this air removed the rubber is forced under the pressure employed into the interstices of the fabric lining, and-a very intimate and close union of the lining'with the rubber is secured which is of great importance. 4

It will be noted that the essential characteristics of my envelop'are that it shall be as thoroughly flexible as possible, and shall be capable of excluding the air when the air has beenwithdrawniand the envelop sealed. Aswill'be obvious the' more nearly a complete vacuum is obtained within the envelop beneath the better will be the result. However, for

phshed by the employment of a narrow of vulpractical purposes, a vacuum of from' 20 to I 21 inches whlch can be quickly and readily obtained and which will yield a pressure of about l bs.- to the squareinch is very satisfactoryin use. The slight remaining air in the envelop has so little free oxygen as t'o'be almost negligible inits eiiect on the rubber Compound being vulcanized. .I have obuse of an air pum' .tained very good results by removing mostof the air, 'or the excess of .air without the my hands, after the shoehas been placed therein,- to collapse. the envelop forcing 1ts sides against the shoe and then further expressing by manipulation as much of the air article to-be vulcanized and much of the benefit results which is obtained byvnlcaniz ing in the absenceof air. There is very litserves as a protection. against the injurious efi'ects of the steam heretofore referred .to,

- and also as a means of the more even and proper :distribution of the pressure of the -steam over the'surfaces of theshoe, while quick vulcanization may, as will be obvious,

' be obtained. a As will further be obvious, if no attempt is made even by hand manipulation' of the envelop to press out the excess of the'air, but the shoe is simply inserted and the envelop closed and the process of vulcanization is then carried out, there will under these conditions be-a substantial exclusion of oxidization as compared with what ordinarily occurs, and to that degree 'a consequent beneficial effect, and all the benefits'ot'. the envelop in protecting the com- I pound fro 'u tho injurious cfl'ccts ofnthe steam andmmsture will be obtained.

I have referred to the employment of steam as a heating agent, in vulcanizing by my process because when stcamcan be used without injurious ellccts, as it can he by my method, it is in my opinion the most desirable heating agent, yielding the heat and pressure desired..con\'cn.iently and economically and is auncdimn known and understood by those skilled in this art. it will he obvi ushowever that a shoe or other article incased in an envelop as heretofore described from which air has been withdrawn may be vulcanized by the application of heat in auy well known manner, as for example,

i by the dry air process or by the employment of air or gas under pressure.

Although l have lwrcinbefore more partirllizlriv (lost-ritual -mv uovcl )rocess as a 1-- hereinbeforedescribed. or other suction'device by simply manipu atingfthe envelop with tle air within theenvelop and envelop .plied to the vulcanization of boots and shoes,

1t will be unde rstood that this process 1s .equally applicable tothe vulcanization of 6 othenarticles, such, for example, as rubber tires, fitted to suitable cores'or forms, correspondlng in function,- inflkeeping the softunvulcanized rubber articles mshape, to v the lasts on which unvulcanized boots and7 shoes are fitted in the vulcanization process What I claim is cam'zing rubber articles which consists in placing an article of unvulcanized rubber, 1n soft condltion, on a form, mclosing' the 'form with the article thereon in an impel viousjba -1ikej flexible envelop which will exclude al air or steam, so that no air ex- Bl) cept what may benaturally contained with! v in the envelop. can come in contact. with said article, placing the inclosed article in'a'vulcanizlng. chamber, and then submitting said article in said chamberto pressure. and heat by means of, a heated fluid, and maintaining the-heat and pressure for-a -time"'sufli- 'cient to vulcanize' the article.

2. The herein described process of vulcanizing rubber bootsv or shoes which consists 'in placing a boot or shoe of u'nvulcanized ,rubber, insoft condition, on a last, inclos-- ing the last "with the boot o'r shoe thereon in an impervious flexible envelop which will exclude air or steam, to avoid oxidation, 95, Y placlng the mclosed boot or shoein a vul canizing chamber, and then submitting said boot, or shoe' in said chamber to the simultaneous" action of heat and pressure by a fluid heated to a vulcanizing temperature,

and maintaining the heat and pressure for a time suflicient to vulcanize the boot or shoe. 3. The herein described process of vu 1 canizing rubber articles which consists in placing an artlcle of unvulcanlzed rubber, in

soft condition, on a form, IHClOSIHg the form with the article thercon'in an imperviousflexible envelop which will exclude air or steam, removing the excess. of air from the envelop to avoid oxidation, placing the incloscd article in a vulcanizing chamber, and, then sulunitting saidarticle in said chamber to the simultmrcous action of heat and pressure by a [luidheaticd to a vulcanizing ternporaturc, and maintaining the heat and pressure for, a time .sullicientto vulcanize the article.

In testimony whereof I aliix my signature, in presence-oi two witnesses.

XVILLIAM G. TITLE.

Witnesses \IVILLIAM A. MAoLnon,

Amen Tl. Monmsou.

11. The herein described process of yul'-.

man, 

